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Naming and Writing Formulas

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Presentation on theme: "Naming and Writing Formulas"— Presentation transcript:

1 Naming and Writing Formulas

2 Types of Compounds There are two types of compounds. Ionic: Covalent:
a metal and an nonmetal Covalent: contain two nonmetals

3 Ionic Compounds Must contain a positive ion (cation) and negative ion (anion). The cation (metal) is written first, the anion (nonmetal) is written second. The total charge on the compound must equal 0.

4 Naming Binary Ionic Compounds
#1 – Name the metal (written on periodic table) #2 – Name the nonmetal, changing the ending to –ide. Examples: MgO CaCl2 NaBr Sr3P2 magnesium oxide calcium chloride sodium bromide strontium phosphide

5 Writing Formulas The subscripts tell how many of each atom you have. (The overall charge must equal zero!!) EXAMPLE: Write the chemical formula for the compound containing Al and Br. #1 – determine the charges Al Br-1

6 Al+3 Br-1 AlBr3 #2 – cross the charges.
#3 – Write the formula, simplify if needed AlBr3 1 3

7 Try this one… Write the chemical formula for the compound containing Mg and S #1 – determine the charges Mg S-2

8 Mg+2 S-2 Mg2S2 MgS #2 – cross the charges.
#3 – Write the formula, simplify if needed Mg2S2 MgS 2 2

9 Ionic Compounds with Polyatomic Ions
#1 – name the 1st part of the compound #2 – name the 2nd part If it is a polyatomic ion, DO NOT change the ending If it is a nonmetal, change to –ide. Examples: CaCO3 Na3SO4 (NH4)2S Calcium carbonate Sodium sulfate Ammonium sulfide

10 Writing Formulas: Na+1 OH-1 NaOH
Same rules apply, except if the polyatomic ion gets a subscript you MUST use parentheses around it. Example: Write the formula for sodium hydroxide. Na OH-1 NaOH 1 1

11 Writing Formulas for Polyatomic Compounds
Calcium phosphate Ca PO4-3 Ca3(PO4)2 3 2

12 Aluminum nitrite Al NO2-1 Al(NO2)3 1 3

13 Homework Page 221 Problems 19, 20, 21 and 22 Page 233 Problem 83

14 Compounds Containing Metals with Variable Charges

15 Variable Charges (Transition Metals)
Metals in Group 1, Group 2, Zinc (+2), Silver (+1) and Aluminum only have one charge. The rest have variable charges so we have to tell what charge the ion has in our compound when we name it.

16 Naming #1 – Name the metal.
#2 – Add a roman numeral telling the charge on the metal in parentheses. I-1 II-2 III-3 IV-4 V-5 VI-6 VII-7 #3 – Name the negative ion as before.

17 Example CrO O is a -2 charge
To make a neutral compound, Cr must be a +2. Chromium (II) oxide

18 FeCl3 Cl is a -1 charge There are 3 chlorine ions  -3
The ONE Fe must be a +3 Iron (III) chloride

19 CoCO3 Carbonate is a -2 Co is a +2 Cobalt (II) carbonate

20 Ni3(PO4)2 Phosphate = -3 x 2 = -6
There are 3 nickel atoms so each one = +2 to equal +6 Nickel (II) phosphate

21 Mn(SO4)2 Sulfate is -2, there are two  -4 so the ONE Manganese = +4
Manganese (IV) sulfate

22 Writing formulas: Rules are the same as before.

23 copper (III) oxide Cu+3 O-2 Cu2O3 2 3

24 Manganese (IV) sulfide
Mn+4 S-2 Mn2S4 MnS2 4 2

25 Iron (II) nitrate Fe+2 NO3-1 Fe(NO3)2 1 2

26 Classwork Page 223 Problems 28, 29, 30, 31 and 32 Page 233 Problem 82

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